Contribution to the future French Responsible Building label, which will take consideration of the challenges of the circular economy.
Scientific context: The quantification of the material flows mobilized by a city and a region and their environmental impacts has been the subject of continuous research since the late 1990s, which has led to the development of methods generally referred to as Material Flow Analysis (MFA). Currently, it is a scientific research subject within the industrial and territorial ecology community.
In France, scientific research in this field has been led by Sabine Barles (professor at the Geographie-Cités laboratory of the University of Paris 1) in the framework of the « CONFLUENT » projects funded by the National Research Agency (“Sustainable City” program launched in 2008-09) and “Urban Environmental imprints” of the PIRVE funded by the CNRS (French National Scientific Research Center).
In 2014, an effort to disseminate this method was supported by the French Ministry of Ecological and Solidarity Transition. The latter published a guide on material flow accounting adapted to the regional scale, written by Pascale Repellin, Benoît Duret and Sabine Barles. This guide is based on scientific studies conducted by the authors on the cases of Paris, Île-de-France, Burgundy and Midi-Pyrénées regions.
Knowledge gained from previous research: The Confluent project aimed at improving the knowledge of material flows and to question the local governance of flows, i.e. to increase the knowledge of material and waste flows and to develop local approaches to industrial and territorial ecology. The scientific knowledge developed enabled us to identify issues related to urban and territorial metabolism.
CitéSource is working to contribute to the dissemination of the method for analyzing material flows on a local scale developed by Eurostat and the CGDD (2014) and to the adaptation of the method to the specific local or urban context. The Eurostat-CGDD material flow accounting method is now reaching maturity, which makes it possible to benefit from a stable analytical framework. However, the use of this method requires spatialized statistical data in order to determine import and export flows and emissions to nature, data whose availability and quality are not always sufficient, which then creates uncertainty.
Challenge related to secondary building materials: building materials are the first materials consumed by the city after water. Built environment stocks, buildings and infrastructures, are the most important among the materials accumulated by human society (Krausmann et al., 2017). The development and renewal of cities involves a significant extraction of natural resources that are largely non-renewable and sometimes in scarcity.
In France, the energy transition for green growth law (LTECV) was published in 2015. The political commitment to develop circular economy policies in the field of construction and development has been supported since 2018 with the publication of a circular economy roadmap by the Ministry of Ecological and Solidarity Transition and then by the anti-waste law approved by the National Assembly in 2019. In particular, it has committed to ambitious goals related to the construction and demolition site waste (C&D waste) and the consumption of construction materials: 1) the gradual decoupling of economic growth from the consumption of raw materials, 2) the recycling of 55% of non-hazardous waste by 2020 and 65% by 2025, 3) the recovery of 70% of the waste from building and public works by 2020 and 5) 50% reduction of the quantities of waste sent to landfill sites by 2025.
Challenge: Local secondary construction materials could provide economic, social and environmental benefits for local stakeholders and project owners.